Plate registering system and method of operation

ABSTRACT

A substrate manager for a substrate exposure machine is used, in one example, as a platesetter. As such, it comprises a substrate storage system, containing one or more stacks of substrates, such as plates in one implementation. A substrate picker is provided for picking substrates from the stack of substrates. The substrates are then handed to a transfer system that conveys the substrates to an imaging engine. According to the invention, a substrate registration system is provided upstream of the imaging engine. At least one engaging member is provided for pushing the substrates on the substrate transfer system to a desired position. Preferably, two sets of engaging members are used, one on either side of the plates. This allows angular as well as positional registration.

BACKGROUND OF THE INVENTION

[0001] Imagesetters and platesetters are used to expose the substratesin many conventional offset printing systems. Imagesetters are typicallyused to expose the film that is then used to make the plates for theprinting system. Platesetters are used to directly expose the plates.

[0002] For example, plates are typically large substrates that have beencoated with photosensitive or thermally-sensitive material layers,referred to the emulsion. For large run applications, the substrates arefabricated from aluminum, although organic substrates, such as polyesteror paper, are also available for smaller runs.

[0003] Computer-to-plate printing systems are used to render digitallystored print content onto these printing plates. Typically, a computersystem is used to drive an imaging engine of the platesetter. In acommon implementation, the plate is fixed to the outside or inside of adrum and then scanned with a modulated laser source in a raster fashion.

[0004] The imaging engine selectively exposes the emulsion that iscoated on the plates. After this exposure, the emulsion is developed sothat during the printing process, inks will selectively adhere to theplate's surface to transfer the ink to print medium.

[0005] Automated systems exist for handling the substrates before andafter exposure in the imaging engine. These management systems typicallypick individual substrates from cassettes and then feed the substratesto the imaging engine. Thereafter, the substrates are unloaded andpassed on for further processing.

SUMMARY OF THE INVENTION

[0006] The plate must be properly feed into the imaging engine. Theseare high-resolution devices. They can compensate for some angular andpositional misalignment of the plate on the drum, but if the positionalor angular misalignment is too large, it can impact the performance ofthese imaging engines.

[0007] The present invention is directed to a substrate registrationsystem for a substrate exposure machine, such as a platesetter orimagesetter. Specifically, it moves the plate or substrate to a known ordesired position, so that the plate or substrate can then be properlyinserted into the imaging engine and typically installed around itsdrum. Such registration is critical to the proper handling of plates inthese plate management systems.

[0008] In general, according to one aspect, the invention features asubstrate registering system for a substrate exposure machine. In atypical example, the substrate exposure machine is a platesetter orimagesetter. The substrate registering system comprises a substratetransfer system for supporting and conveying substrates in the substrateexposure machine. At least one engaging member is provided for pushingthe substrates on the substrate transfer system to a desired position.

[0009] In a current implementation, the substrate transfer systemcomprises a frame and a series of rollers for supporting the substrates.The rollers are driven to convey the substrates relative to thesubstrate transfer system in the fashion of a conveyor. Typically, thesubstrates are moved from a substrate store to the imaging engine.

[0010] The engaging members extend typically in a direction that isorthogonal to the plane of the substrate transfer system. The engagingmembers move in a direction that is perpendicular to a direction inwhich the substrates are conveyed by the substrate transfer system. Inthis way, they can push the substrates to the desired position on thesubstrate transfer system.

[0011] In a preferred embodiment, at least one right engaging member andat least one left engaging member are provided to contact opposed sidesof the substrates. In this way, they can move the substrates to adesired position, typically in the center of the substrate transfersystem. This also allows the substrates to be angularly aligned.

[0012] In general, according to another aspect, the invention alsofeatures a method for moving plates in a platesetter. This methodcomprises picking plates from a plate store. The plates are thenconveyed to an imaging engine for exposure. Prior to loading the platesin the imaging engine, however, the plates are registered to a desiredposition.

[0013] The above and other features of the invention including variousnovel details of construction and combinations of parts, and otheradvantages, will now be more particularly described with reference tothe accompanying drawings and pointed out in the claims. It will beunderstood that the particular method and device embodying the inventionare shown by way of illustration and not as a limitation of theinvention. The principles and features of this invention may be employedin various and numerous embodiments without departing from the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the accompanying drawings, reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale; emphasis has instead been placed upon illustratingthe principles of the invention. Of the drawings:

[0015]FIG. 1 is a schematic, side plan view of a plate manager accordingto the present invention;

[0016]FIG. 2 is a perspective view showing the substrate transfer systemand the substrate registration system according to the presentinvention; and

[0017]FIG. 3 is a schematic perspective view showing the inventivesubstrate registration system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018]FIG. 1 shows a substrate, and more specifically a plate, manager20, which has been instructed according to the principles of the presentinvention.

[0019] Generally, the plate manager 20 comprises a plate store 200, aplate transfer system 400, a plate inserter 600, and a plate imagingengine 500, all of which are controlled by a system controller 50.

[0020] The plate storage system 200 comprises, when loaded, multiplecassettes 210. Each of these cassettes 210 holds a stack of plates 212.The cassettes are moved vertically within the plate store 200 by acassette elevator or lifter 214.

[0021] In one example, the cassettes themselves are stored in stacks ofcassettes and moved vertically by the cassette elevator 214 so that thestack of plates 212 of a specific cassette 210 is raised to the level ofa plate picker system 216. Once the cassette 212 is at the properheight, it is moved laterally. The cassette 212 is thereby positionedunderneath the plate picker system 216, which then picks a plate off ofthe stack of plates 212.

[0022] The plate picker system 216 provides individual plates from thestack of plates 212 to the plate transfer system 400. This transfersystem 400 currently comprises a conveyer 410 that receives the plate 10and then moves the plate 10 laterally in the plate manager 20 toward theplate imaging engine 500.

[0023] Between the plate imaging engine 500 and the transfer system 400is a plate inserter system 600. The angle of the plate is moved from agenerally horizontal orientation as it is received from the transfersystem 400 to a more vertical orientation to be compatible for insertioninto the plate imaging engine 500. Specifically, the plate is angled at75 degrees from horizontal for insertion into the engine.

[0024] Specifically, the plate inserter system 600 comprises an inserterarcuate transfer path 610. It moves the plate from its horizontalposition as it is transferred across the conveyer 410 to a more verticalorientation. Specifically, it transfers the plate 10 so that it isreceived by a first set of output pinch rollers 612.

[0025] The plate imaging engine 500 receives the plate 10 from the plateinserter system 600. The plate is brought into engagement with a headerclip 510 on the exterior of drum 512 of the imaging engine 500. The drum512 is then advanced so that the plate 10 is progressively installed onthe outside perimeter of the drum 512 by ironing roller 540 until atrailing edge clip 514 engages its trailing edge.

[0026] At this stage, the plate 10 is selectively exposed by a laserscanning system 516. Typically, this is a high speed, high power laserscanning system that selectively exposes the emulsion on the plate 10with the desired image, in a raster fashion. Afterward, the plate 10 istypically ejected from the plate imaging engine 500 to further machinesfor development and further processing.

[0027]FIG. 2 shows the plate conveyer 410 of the plate transfer system400. It comprises a series of rollers 620. These rollers are supportedto rotate on a right frame member 622 and a left frame member 624. Theserollers 620 generally form an upper planar surface on which the plate 10is supported.

[0028] A roller drive belt 628 strung over on a series of conveyorpulleys 626 that are disposed between each of the rollers 620. As aresult, the roller drive belt 628 is urged into engagement with theouter surfaces of the rollers 620. Thus, when a roller drive motor 630is driven under the control of the controller 50, the roller drive belt628 causes the rollers 620 to rotate in a counter clockwise directionand thereby move or convey the plate 10 in the direction of arrow 11 tothe imaging engine 500.

[0029] The inventive substrate registering system comprises a set ofengaging members 710. In the orientation of FIG. 2, only the leftengaging members 710-1 are shown. There is, however, a second set ofright engaging members in the preferred embodiment.

[0030] Each one of the engaging members 710 comprises a wheel 712 thatis held generally at the plane of the substrate 10. The wheels 712 areoriented to rotate around an axis that is orthogonal to the plane of theconveyer 410 and thus plate 10. As a result, they can engage the sidesof the substrate 10, even while the conveyer 10 is conveying the plateor substrate 10 in the direction of arrow 11.

[0031] The wheels 712 are supported on respective wheel axles 714.These, in turn, project upwards from a rack 716.

[0032]FIG. 3 shows the substrate registering system with the conveyer410 removed and portions of the right and left frame members 622, 624cut away. Specifically, there is a set of left engaging members 710-1and a set of right engaging members 710-2. These members, in turn, aresupported by a respective left rack 716 and a right rack 730. The racks716 and 730 are supported to ride or slide on a front rail 720 and rearrail 718, which are supported by the right and left frame members 622,624. As a result, the racks 716 and 730 are held in a parallelorientation relative to each other and extend in the direction of platetravel, see arrow 11.

[0033] The racks 716, 730 are free to slide in the direction of arrows740. As a result, when the racks are moved toward each other, the wheels712-1, 712-2 are moved toward each other to thereby engage a platebetween the left wheels 712-1 and the right wheels 712-2. This movementand engagement causes the plate 10 to be brought into angular alignmentand centered in the middle of the conveyor 410.

[0034] In the present embodiment, the left rack 716 and the right rack730 are moved using a combination of a timing belt 732, timing beltpulleys 734, 736 and a rack drive motor 738. Specifically, the left rack716 is connected to a proximal side of the timing belt 732, seeconnection point 752, whereas the right rack 730 is connected to theother, or distal, side of the timing belt 732, see connection point 754.As a result, when the timing belt 732 is advanced in the direction ofarrow 756 (clockwise), the left rack 716 and the right rack 730 aremoved away from each other to thereby disengage from a plate 10 that islocated between the left wheels 712-1 and the rights wheels 712-2

[0035] In contrast, when the timing belt is driven by the motor 738 tomove in the direction of arrow 758 (counterclockwise), the right rack716 and the left rack 730 are moved toward each other to thereby bringthe wheels 712-1, 712-2 into engagement with the plate 10 on theconveyer 710. This results in the plate 10 being centered on theconveyor 410 and brought into angular alignment.

[0036] While this invention has been particularly shown and describedwith references to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the scope of the inventionencompassed by the appended claims.

What is claimed is:
 1. A substrate registering system for a substrateexposure machine, the substrate registering system comprising: asubstrate transfer system for supporting and conveying substrates in thesubstrate exposure machine; and at least one engaging member for pushingsubstrates on the substrate transfer system to desired positions.
 2. Asubstrate registering system as claimed in claim 1, wherein thesubstrate transfer system comprises a frame and a series of rollers forsupporting the substrates.
 3. A substrate registering system as claimedin claim 2, wherein the rollers are driven to convey the substratesrelative to the substrate transfer system.
 4. A substrate registeringsystem as claimed in claim 1, wherein the substrate transfer systemconveys the substrates from a substrate storage system to an imagingengine.
 5. A substrate registering system as claimed in claim 1, whereinthe at least one engaging member extends is a direction that isorthogonal to a plane of the substrate transfer system.
 6. A substrateregistering system as claimed in claim 1, wherein the engaging membermoves in a direct that is perpendicular to a direction in which thesubstrates are conveyed by the substrate transfer system.
 7. A substrateregistering system as claimed in claim 1, further comprising multipleengaging members engaging along at least one side of the substrates. 8.A substrate registering system as claimed in claim 1, further comprisinga rack for supporting the engaging members.
 9. A substrate registeringsystem as claimed in claim 1, wherein the substrate transfer systemcomprises a frame and a series of rollers for supporting the substrates,and the at least one engaging member projects upward through a plane ofthe series of rollers to enable contact with substrates supported on therollers.
 10. A substrate registering system as claimed in claim 1,wherein the at least one engaging member comprises a wheel.
 11. Asubstrate registering system for a substrate exposure machine, thesubstrate registering system comprising: a substrate transfer system forsupporting substrates; and at least one right engaging member and atleast one left engaging member for contacting opposed sides ofsubstrates to push the substrates on the substrate transfer system to adesired position.
 12. A substrate registering system as claimed in claim11, wherein the right engaging member and the left engaging member aredriven in an opposed fashion to center the substrates on the substratetransfer system.
 13. A substrate registering system as claimed in claim11, wherein the right engaging member and the left engaging member aredriven in an opposed fashion to angularly align the substrates on thesubstrate transfer system.
 14. A substrate registering system as claimedin claim 11, wherein the substrate transfer system comprises a frame anda series of rollers for supporting the substrates.
 15. A substrateregistering system as claimed in claim 14, wherein the rollers aredriven to convey the substrates relative to the substrate transfersystem.
 16. A substrate registering system as claimed in claim 11,wherein the substrate transfer system conveys the substrates from asubstrate storage system to an imaging engine.
 17. A substrateregistering system as claimed in claim 11, wherein the at least oneright engaging member and the at least one left engaging member extendis a direction that is orthogonal to a plane of the substrate transfersystem.
 18. A substrate registering system as claimed in claim 11,wherein the at least one right engaging member and the at least one leftengaging member move in a direct that is perpendicular to a direction inwhich the substrates are conveyed by the substrate transfer system. 19.A substrate registering system as claimed in claim 11, furthercomprising a drive motor and a timing belt that driven by the drivemotor, each of the right engaging member and the left engaging memberbeing connected to the timing belt to be moved by the drive motor.
 20. Amethod for moving plates in a platesetter, the method comprising:picking plates from a plate store; conveying the plates to an imagingengine for exposure; and before loading the plates in the imagingengine, registering the plates to a desired position.
 21. A method asclaimed in claim 20, wherein the step of registering the platescomprises pushing the plates to a center position.
 22. A method asclaimed in claim 20, wherein the step of registering the platescomprises angularly aligning the plates.
 23. A method as claimed inclaim 20, wherein the step of registering the plates comprises movingthe plates in a direction that is perpendicular to a direction in whichthe plates are conveyed by the imaging engine.